全額自己負担で払うことは次のように言えます。
ーto pay the whole cost oneself
ーto pay the entire bill yourself
例:
I have to have a colorectal cancer screening, but I have to pay for the entire bill myself, so my monthly expenses will be really high this month.
「大腸がん検診を受けなければいけないが、全額自己負担なので今月の出費はすごく大きいだろう」
to have a colorectal cancer screening「大腸がん検診を受ける」
to pay for the entire bill myself「全額自己負担で払う」
expenses「支出・出費」
ご参考まで!